If that doesn't work you can always work with you config folder. Located at, C drive, game, paintball 2, pball, configs. After you get in there you can simply type in your controls, but make sure to use "quotes". So what Jitspoe typed would be
bind "a" "+moveleft"
bind "w" "+forward"
bind "s" "+back"
bind "d" "+moveright"
bind "mouse2" "+moveup"
bind "shift" "+movedown"
A lot of the DP community don't work with config folders because they are a hassle, but they may be your only option.
Hope you are able to figure it out. Good Luck.